There is an enormous demand for chemical sensors in many areas and disciplines. High sensitivity together with ease of operation is the major issue that need to be addressed in the development of sensors. Fluorescence based sensors appear as most promising for chemical sensing. However, the development of sensors is not trivial; material science, molecular recognition and device implementation are some of the aspects that play a role in the design of sensors. A number of materials such as silica particles, glass and gold surfaces, quantum dots, Langmuir-Blodgett films, vesicles, liposomes, and such like are used combined with many chemical receptors to create sensitive fluorescent materials.
Of late, polypeptides in particular, silk fibre have been used extensively in various bio applications like drug delivery, tissue engineering etc due to its biocompatibility. Several attempts have been reported in literature to improve the fiber properties of silk by grafting with various polymerizable monomers. On the other hand, researchers have tried to make use of the self assembling ability of oligopeptide units to form hierarchical assemblies of conjugated polymers.
Modification of silk to achieve tunability in properties such as mechanical strength, water absorbance, rheological properties and such like have been studied in the past.
Silk combined with plastics or fabricated with other biopolymers for use in the fields of microimaging, biological detection, optoelectronics are also studied.
An article titled “Oligo(p-phenylenevinylene)-Peptide Conjugates: Synthesis and Self-Assembly in Solution and at the Solid-Liquid Interface” by Rachid Matmour, Inge de Cat et al. in Am. Chem. Soc., 2008, 130 (44), pp 14576-14583 disclose synthesis of two oligo(p-phenylenevinylene)-peptide hybrid amphiphiles using solid- and liquid-phase strategies. The amphiliphiles are composed of a π-conjugated oligo(p-phenylenevinylene) trimer (OPV) which is coupled at either a glycinyl-alanyl-glycinyl-alanyl-glycine (GAGAG) silk-inspired β-sheet or a glycinyl-alanyl-asparagyl-prolyl-asparagy-alanyl-alanyl-glycine (GANPNAAG) β-turn forming oligopeptide sequence.
An article titled “One-Dimensional Optoelectronic Nanostructures Derived from the Aqueous Self-Assembly of π-Conjugated Oligopeptides” by Stephen R. Diegelmann, Justin M. Gorham, and John D. Tovar demonstrate how small peptide sequences with π-conjugated oligomers can be directly embedded in the backbone, promote assembly into 1-D nanostructures with strong π-π intermolecular electronic communication under completely aqueous and physiologically relevant conditions.
US2012039813 relates to a method for producing luminescent coloured silk fibroin. The invention also relates to the use of luminescent coloured silk fibroin to produce threads, yarns or fabrics and in biomedical applications. US'813 disclose a method in which the silkworms are fed with a luminescent dye which is further degummed to obtain the coloured silk fibroin. The luminescent dye is selected from the group consisting of pyrene derivatives, xanthenes derivatives, cyanine derivatives, napththalene derivatives, coumarin derivatives, oxadiazole derivatives, oxazine derivatives, acridine derivatives, arylmethine derivatives and tetrapyrrole derivatives.
WO2009023287 relate to a composition comprising a fluoroionophore grafted to a self-plasticized polymer matrix. The fluoroionophore is lipophilic and H<+>-selective, namely Nile Blue or an analog. The fluoroionophore is grafted to the matrix via a functional group, wherein the matrix comprises an acrylate copolymer, and the fluoroionophore is covalently linked to the matrix through a functional group on the acrylate copolymer.
However, no attempt has been made to graft silk with π conjugated oligomers and polymer with fluorescent probes for possible application in optoelectronics.